Centrifugal type speed governing mechanism



" No v. 6, 1945. H. M. OTTO l 2,388,282

CENTRIFUGAL TYPE SPEED GOVERNING MECHANISM WM i' /3 f4 f6.

hve'tor:

2;/ f\ Harold M. CD1-,+505y --H-b y HIS Attorney.

`perienced in case of Patented Nov. 6, 1945 CENTRIFUGAL TYPE srEEDG,vERNINGm l MEoHANrsM g Harold M. Otto, Schenectady, N. Y., assignor toGeneral Electric Company, a corporation of New York Application February19, 1942, seri-a1 No. 481,604f 7 claims. (el. 264-17) The presentinvention relates to centrifugal type speed governing mechanisms forcontrolling or actuating a machine element in response to speed changesor upon the occurrence of certain speed conditions. The invention is ofparticular significance in connection with centrifugal type emergencygoverning mechanisms although it is not necessarily limited thereto.Such mechanisms are used, for example, for shutting down prime moverssuch as elastic fluid turbines as their speed rises `a certainpercentage above the norma1 operating speed. In elastic fluid turbinearrangements it is in general customary to provide an emergency speedgovernor for closing the turbine stop and control valves when the speedrises about 10% above normal speed. Emergency governors in sucharrangements constitute the final safety device of the turbine and forthis reason should be in perfect operating condition. As it rarelyoccurs that an emergency governor has to operate to effect shutdownlof aturbine, it is customary to test the governor at frequent intervals,particularly during starting and shutdown'of the turbine, to assure thatit is in safe operating condition. It is not desirable to carry out thetesting or checking of the governor at the actual emergency speed forwhich the governor is designed and for this reason arrangements havebeen devised whereby the governor may be tested at a speed below theemer- Y gency speed. One such arrangement is disclosed in the patent toW. P. Dryer, No. 1,666,490, issued April 17, 1928, and assigned to thesame assignee as the present application. According to thesearrangements the mass of the flyweight is increased by the supply ofliquid such as oil to a chamber formed by the ilyweight. Thus agoverning mechanism designed normally to act on an element at a speed of2000 R. P. M. may be caused to actuate such element at a lower speed,`

say 1000 R. P. M., by the supply of oil to a chamber formed in itsflyweight. Diliiculties are exgoverning mechanisms designed to operateat'higher speeds of the order of 5000 R. P. M. and more when it isdesired to test such mechanisms at much lower speeds of the order of1000 R. P. M. The methods and arrangements heretofore used wouldnecessitate the provision of ilyweights forming very large chambers topermit the supply of an amount of liquid suicient to cause actuation ofthemechanism at much lower speed. I f

One object of my invention is to provide an improved construction andarrangement of governing mechanisms; which may be used as emer- .port orcylinder I3 gency governors and readily tested at a compara` tivelysmall fraction of their normal operating` speedby a relatively smallchange of the mass of one of their flyweights.

'Another object of my invention is to provide a governi-ng mechanismwith an improved and readily variable governor characteristic.

These and other objects are accomplished' in accordance with myinvention by the provision of a governing mechanism which includes atleast two yweights arranged to produce centrifugal forces opposing eachother and producing together a differential or resultant actuating forcefor controlling or actuating a machine element. Each of the yweights isbiased by a separate spring against its centrifugal force. By properlychoosing the spring characteristics, the masses of the flyweights andtheir normal radii of rotation, a governing mechanism may be produced inwhich the ratio of the centrifugal forces of the two fiyweights variesin a desired manner with variations in speed.

For a better understanding of what I believe to be novel and myinvention, attention is directed to the following description and theclaims appended thereto in connection with the accompanying drawing.

In the drawing Fig. 1 illustrates a governing mechanism embodying myinvention; and Fig. 2 is a section along line 2-2 of Fig. 1.

The arrangement illustrated in the drawing comprises a shaft I0 whichmay form part of an elastic fluid turbine and an emergency governingmechanism or unit Ilfsecured to the end of the shaft I0. The mechanismis arranged in cooperative relation with an element, in the presentinstance a trip finger I2, to cause shutting of turbine valves, notshown, as the turbine speed rises a certain percentage above tlie normaloperating speed. The governor unit includes a supwhich has one endrigidly fastened to the shaft VIll and another end to which a .cover I4With'a central opening' I5 is secured. The cylindrical support I3broadly constitutes a hollow extension of the shaft I0. Diametricallyopposite portions of the cylindrical support I3 haveopenings I6, I1forming seats for plugs or bushings I8 and I9 respectively. A governorspindle 20 vprojects through the plugs I8, I9 and has end portionslocated outside the support and connected to an emergency ring or mainflyweight 2 I. The spindle 20 has sliding t in the bushing I8 and isrigidly secured to the bushing I9, which latter has sliding fit in thesupport I3. The main flyweight 2l comprises axially spaced rings 22 and23. The lower halves of the rings are united by an outer wall 24 whichhas end portions 25 turned inward and suitably secured to the adjacentsurfaces of the rings 22, 23. The central portion of the outer wall 24forms a boss 26 which has screw-thread connection with the lowerthreaded, end of the spindle 2.0:. The outer wall.

24 and thev side; walls. form two .cups or chambers.

21, 28 with discharge openings 29 and 30 respectively. During rotationliquid may be conducted' into the chambers 21, 28 by avalvedliquidsupply conduit 3l through axial' openings` 32 with radialdischarge ports 33 in the cylindrical support I3.

Upper portions of the amallyspaceds rings 23 are united by a spacer orplug 34 with a central bore 35. The upper end: ofthe spindle projectsinto the bore 35 and has a slot36 looselyV Cil .whereas the auxiliary orsecond yweight 44 tending. to move upward is biased downward by il the.Vspring 46; Thus, the forces of the two yweights are in opposition andthe resultant of .theitwmforces is;.the;.di1erential thereof. Thisdilerential is a..function of the masses of the ilyweights; the radiusat which they rotate, the

`characteristicsorthe. springs opposing them and the speed. At lw speedthe centrifugal force on The threaded portion 4L of the spindle has adiametrical slot 43 for accommodating the pin 42. indifferent positionsof the ring. 40. Upon removal of the pin 42, the ring 4U. maybe turnedone half. or vam-ultiple of one half turn and, thereafter. the pin. 4.2can be reinserted into the slot. 43.'. The mechanism. so far described.is typical f or arrangements heretofore used. During operation thespindle 2i); withthe flyweight'2l is normally heldin the position.shown` in the drawing by action. of the. spring 3&- counteracting. theVcentrifugal force on the flyweight. If vthe speed rises beyondvnormal.operating speed the yweight 2| is gradually forced outward, that is,downward whenviewed in the drawing, against'the biasing force; ofthe-governor spring 38; At emergency speed, which. may be*` 10%above-:normal operating; sp, eed, the.r main; flyweight engages-the tripfinger l2 which in turn causes.- through. known mecha-nisms, notv shownythe turbine valves Ato close.. The mechanismrmay-he tested at. lowerspeeds by supplying liquid; froms the conduitJ 3.1 to thechambers-215,28 ofZ the. main flyweight.. VDuring testing-the increasein. mass ofr the mainflyweight caused bvthesupply of liquid to the.chambers f, 2.8 effects tripping or operation of the. mechanisrrr atgalowerspeed The-liquid isdischarged from the; c l'lambersT 2.7,. 2 8.through the aforementionedropenines: 29..` which asindicatedk in thedrawing; are; substantially smaller than the supply- Openings or.Aportsl 33.

lf: such mechanism were designed. for a normal operating. speed of- 5000R. E. M. or higher thechambers 21?,A 2.8` would have to be made, ofconsiderable size to permit testing` of the mechamism-ata: low speedeof; ,say 1`000.R. P. M.

In; accordance withmy invention as indicated above-, I provide; meanspermitting, suchvv governor whenused as an emergency governor to betested at a. small fraction of. its normal operating speed. Thisgmeansin. the; embodiment shown in the drawinggineludesan auxiliary orV secondlyweight comprising; a ring- -44=v surrounding thespindle 20 inside thevcylindrical suppDr-t I3 and -biasedtowards.` ai. shoulder; 45 formed`by;l theaforementionednut 4 bymeans ofa spring: 45; having a lower endengaging the ring 44 and an upper thelfrst flyweight is comparativelylarge and that on the second yweight is.. comparatively small. Thiais.direnot. o nl'yQto.v the fact that. the second iyweight` 44 hasa muchsmaller mass' than the first ilyweight, ZI'. b ut primarily `due to thefact that, the, second. flyweight 4'4" has. a. center of gravity.4.1.-.' which at. low speed. isV located close to the center, of.rotation. moi4 the system while the-.first flyweight. 2J. has. a.comparatively great mass.' with a. center. of. gravityv 4,9v at agreater distance ory radius from. the, center of.. rotation.

The whole system. at. low speed has av center ofgravity 5,5 which` inyFig.. 2 is located. below the center of` rotation. andnaturally abovethe. center of. gravityv 49. of theirstflyweightin the position shown.in the drawing.. As-.the second flyweight at. low, speed. produces aicomparatively smallforce. in.. opposition to. the greatericen.-

trif-ugalfforce, of therst flyweight it is possible tocauseactuation ortripping of: the mechanism atflowspeedlby the. supply of a comparativelysmall-amount-of.1iquid,tovthe chambers` 21, 28. Inother words, it is-.possible at-V low speed to overcome;l the opposing, forceoi'- thesecondv fly- 33,; Withincreasing. speed; the second` flyweight is,moved. outward,. thatv is; upward. in. the drawing, until .f at a.certain-speed it reaches the position. indicatedaindash-dotted lines lin. Fig. 2. Its-center or grav-ity` 41; thenVv has-moved'. upwardl aconsiderable distance Yinto the position.4 5I.. Let us assume.-that-during.. this` movement of the Vsec.- ond.Y yweight. 44- the firstVflyweight 2|.- has-A remained; in;its` original; position tdue to thebiasing effect of thefcomparatively-strong spring 38. rI'he center of,gravity-Emol theentire system. then mustv havemoved upward-into anewposition. 52. With a furtherfincrease in speedy thefrcentrifugal forceexertedeon` the, iirst flyweight 2|-, overcomes the; force of thespring;A 3.8.' togetherI witlr the -opposing; force.Y eff; thesecond-iiyweight. The main flyweighttogether with. the spindle ism'ovedfout.- ward, that is. downwardin.- thedrawing, to' engage.theelement I2.. Under.- this condition: the centenof. gravity lia-of..the rst-iiyweightisfmoved outward.into.theposition.53.. Ifft-he normaloperatingl speed of, the turbine. to f which the governor isattachedis.500`0-R..l?. M.,l outwardmovement of the. main.. governor.. weight.and. trippingI of. the finger IZnay take. placeata speedof; say 5500 R.P. M.

If the turbine hasbeen .operating at normal the val'ved conduit 31' isopened andY oil or like liquid-is lsupplied to the chambersll, 28 tocause tripping. of themechanism;

Thus,; this mechanism may be tripped at a speed near itsl normal'operating speed by the supply of oil-to the chambers 21, 28 and itmaYalso` be tripped atal considerably lower speed of ample, at one fifth ofthe normal operating speed the centrifugal force exerted on the secondflyweight may be equal to one fifth only of the centrifugal forceexerted on the rst yweight, whereas at a speed equal'to three fths ofthe normal operating speed the centrifugal force created by the secondflyweight is greater than three fifths of the centrifugal force createdby the first flyweight.

The governor may be readily adjusted by changing the position of the nutlll!V on the spindle 20. If the nut 40 is turned downward on the spindlethe initial compression of the spring 38 is increased and that of thespring 46 is simultaneously decreased, resulting in a higher trippingspeed. The action of the governor may be further varied during'operationby changing the ratio of mass of the two flyweights. This isaccomplished in the present instance by supplying liquid from the valvedsupply conduit 3l to the chambers or cups 21, 28 of the main flyweight 2I. This liquid supply means accordingly broadly constitutes a means forvarying the mass of one of the yweights during operation. At certainhigh speeds the flyweights are stopped from further outward movement andthereby rendered inoperative by the cylindrical support I3. As the rstflyweight is forced outward its upper portion in the drawing, that is,the spacer 34, engages the adjacent wall of the cylindrical supportwhich latter constitutes a stop limiting outward movement of the mainiiyweight. Similarly, at a certain high speed the second yweight 44engages a cylindrical projection or stop 55 forming an extension of thebushing I9 preventing further outward movement of the latter. In placeof the rigid projection 55 flexible or yieldable means, such as anadditional spring, may be provided which above a certain speed aids thespring i6 in biasing the second flyweight 44 against centrifugal force.

Having described the method of operation of my invention, together withthe apparatus which I now consider to represent the best embodimentthereof, I desire to have it understood that the apparatus shown is onlyillustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

l. Centrifugal type speed governing mechanism comprising a support, arst flyweight, means including a spring biasing the first flyweighttowards the support, a second llyweight and a biasing spring engagingthe second flyweight and arranged to counteract movement of the rstiiyweight during operation, the flyweights having centers of gravitylocated on opposite sides and at different radii from the center ofrotation of the support, and means connected to the iiyweights andmovable in response to changes of the differential centrifugal force ofthe iiyweights.

2. Centrifugal .type speed governing mechav nism comprising a?cylindrical support, a spindle slidably projecting `throughdiametrically oIJPOr. site openings in the support, a mainflyweight se.cured to an end of thespindle outside of thesupport, a biasing spring`surroundingthe spindle inside `'the support to oppose movement ofthespindle by action of centrifugal force exerted on the main fiyweight,an. auxiliary iiyweight surrounding the spindle inside the support, anda spring engaging the spindle and the auxiliary flyweight opposingcentrifugal force exerted on the auxiliary nyweight, the centers ofgravity of the flyweights being located on opposite sides of the axis ofrotation and the auxiliary `flyweight being arranged to oppose movementof the spindle by action of the main iiyweight in order to producemovement of the spindle in response to changes of the differentialcentrifugal force of the flyweights.

3. Centrifugal type speed governing mechanism comprising a cylindricalsupport having diametrically opposite openings, a spindle within thesupport having end portions projecting through the openings, a mainflyweight connected to the spindle outside the support, a

spring surrounding the spindle inside the support to bias the mainfiyweight against centrifugal force, an auxiliary flyweight engaging thespindle inside the support to oppose movement of the main flyweight, anda spring surrounding the spindle and engaging the auxiliary nyweight tobias the latter against centrifugal force.

4. Centrifugal type emergency speed governing mechanism comprising acylindrical support having diametrically opposite openings, a spindleprojecting through the openings and forming shoulders inside thesupport, a main iiyweight 40 forming a chamber being secured to an endportion of the spindle outside the support, spring means biasing themain flyweight towards the support and an auxiliary flyweight engagingthe shoulder on the spindle inside the support and a spring surroundingthe spindle and biasing the auxiliary flyweight against centrifugalforce, the

center of gravity of the auxiliary yweight and the center of gravity ofthe main flyweight being located on opposite sides from the center ofrotation and the centrifugal forces of the two flyweights opposing eachother and the center of gravity of the auxiliary iiyweight being locatedat low speed considerably closer to the center of rotation than thecenter of gravity of the main yweight to permit testing of the governorby the supply of a comparatively small amount of liquid into saidchambers at a speed considerably below the normal operating speed.

5. Centrifugal type speed governing mechanism comprising a rotatablesupport, means including first and second flyweights arranged onopposite sides of the center of the support and movable independently ofand in opposition to each other, separate biasing spring means for theflyweights, stop means to limit movement of one of the yweights at apredetermined speed,

one of the flyweights forming a chamber, andk nism comprising meansincluding a flyweight andY a spring opposing movement of the lyweight,

other means including a yweight independently movable of the rstflyweight and opposing move-

